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Open Access

On the Superstability of the Pexider Type Trigonometric Functional Equation

Journal of Inequalities and Applications20102010:897123

Received: 23 October 2009

Accepted: 3 January 2010

Published: 21 January 2010


We will investigate the superstability of the (hyperbolic) trigonometric functional equation from the following functional equations: and , which can be considered the mixed functional equations of the sine function and cosine function, the hyperbolic sine function and hyperbolic cosine function, and the exponential functions, respectively.


Functional EquationExponential FunctionFull ArticleSine FunctionCosine Function

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Authors’ Affiliations

Department of Mathematics, Kangnam University, Yongin, South Korea


© Gwang Hui Kim 2010

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.